Kaia Gerber's best friend spent time in Hawaii just weeks before his untimely death.
23-year-old Daniel Mickelson passed away unexpectely on July 4.
As Radar reported, an investigation has been launched into his death.
Mickelson -- who was a rising actor in Hollywood -- had a huge presence on social media. He was friends with high-profile stars besides Gerber like Paris Hilton, Delilah and Amelia Hamlin, and Brielle Biermann.
Weeks before his death, Mickelson shared photos from his trip to Maui and looked happy in paradise.
Posting several shots to his Instagram, he appeared rested and relaxed while sitting in a bathrobe inside his hotel room.
Mickelson sported a signature Hawaiian lei and joked with the caption, "ISLAND DAN."
He also showed himself muddy while sitting on a four-wheeler and looking over the gorgeous ocean while flashing his contagious smile.
"I don’t always post, but when I do it’s once a month, stay thirsty my friends. btw my thighs are more tan now I promise," Mickelson wrote.
Just last week, Gerber's BFF teased that he was Tarzan and tagged himself "George of the Jungle" in two shirtless selfies.
According to the Los Angeles County Medical Examiner, Mickelson's autopsy has been scheduled, and the exam is pending.
His cause of death and the manner of his passing have yet to be determined.
Officials say Mickelson died on Sunday in an L.A. home.
Following his death, Kaia Gerber posted an emotional tribute to her late best friend.
“I remember that time we sat on the couch and spent the whole day coming up with our own secret language that we continued to speak every time we saw each other. I wish we could go back there. I wish we were still talking in sentences that probably annoyed everyone else but made us crack up every time," the model reminisced.
"I wish I was still sitting on my bathroom floor FaceTiming you, because that was the only place I had wifi and I never wanted to miss a call from you," Kaia continued.
Ending her heartfelt tribute, she said, "Thank you for being the reason for so much laughter and happiness in the world. It won't be the same without you here. I love you Daniel."